There are at least three new variants of the Sober worm spreading across the Internet via e-mail messages. The viruses are activated once a user clicks on an infected attachment. The new variants of Sober...are capable of disabling antivirus programs...

Infected messages may have a random subject line or none at all, Kapersky said. But the attachments can be recognized by their names:
Exceltab-packed_List.exe
Liste.zip
Reg-List-Dat_Packer2.exe
reg_text.zip
Word-Text.zip
Word-Text_packedList.exe
Word-Text_packedList.zip